Area in Louisiana and Eastern Texas. 81 



southwest of Uvalde passed entirely through the Cretaceous into 

 black shale which is believed to represent the Bend. Wells north 

 and west of Uvalde have encountered similar materials below 

 the Cretaceous. The Bend is also well developed in the Pale- 

 ozoic area west of the Pecos. This would indicate that during 

 the Bend the Llano area was a peninsula extending northward 

 from the Llanoria land mass. ' ' 



The extent of the rocks of Pennsylvanian age under- 

 neath the Coastal Plain in eastern Texas is not known, 

 but, as pointed out by Dnmble,*^ they are probably 

 confined to the extreme western and northern borders of 

 the Coastal Plain in that State. Sidney Powers,"^' w^ho 

 has collected much information on deep wells in eastern 

 Texas, says : 



' ' Recent borings, * * * starting in one instance in the Tertiary 

 and in the other instances in the Cretaceous, at Waco, George- 

 town, Maxwell, San Antonio, and Leon Springs, find pre-Cam- 

 brian schist beneath the Cretaceous at depths of 3,700, 1,100, 

 3,000, 1,800 and 1,100 feet, respectively." 



Wells at and near Fort W^orth, Tex., have penetrated 

 sandstone and shale of Pennsylvanian age,*^ and a well 

 at Dallas, Texas, has penetrated rocks of apparently the 

 same age.^^ Wells on the Preston anticline have revealed 

 the presence of the Caney shale, of Mississippian age, and 

 the Glenn formation, of Pennsylvanian age, directly 

 underneath the strata of Lower Cretaceous age, as far 

 southeast as Denison, Texas.^^ * 



In Arkansas no wells have passed through the Creta- 

 ceous rocks south of Nashville. A w^ell at that place 

 penetrated rocks of apparent Carboniferous age.^^ 



■^ Idem. 



*' Powers, Sidney, The Butler salt dome, Freestone County, Texas, this 

 Journal, (4), vol, 49, p. 141, 1920. 



^'Winton, W. M.^ and Adkins, W. S., The geology of Tarrant County, 

 Univ. of Texas Bull. No. 1931, pp. 25, 107-114, March, 1920. 



*^ Fuller, M. L., Kelation of oil to carbon ratios of Pennsylvanian coals in 

 north Texas, Economic Geology, vol. 14, no. 7, p. 541, Nov., 1919. 



^ Hopkins, O. B., Powers, S., and Eobinson, H M., Structure of the 

 Madill-Denison area, Oklahoma and Texas, with notes on the oil and gas 

 development in that and adjoining areas, U. S. Geol. Survey, Bull, (in 

 press.) 



°^ Miser, H. D., and Purdue, A. H., Asphalt deposits and oil conditions 

 in southwestern Arkansas, U. S. Geol. Survey, Bull. 691-J, p. 290, 1918. 



